ioccom.h

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#pragma once
 
/*
 * Ioctl's have the command encoded in the lower word, and the size of
 * any in or out parameters in the upper word.  The high 3 bits of the
 * upper word are used to encode the in/out status of the parameter.
 */
#define IOCPARM_SHIFT   13   /* number of bits for ioctl size */
#define IOCPARM_MASK    ((1 << IOCPARM_SHIFT) - 1) /* parameter length mask */
#define IOCPARM_LEN(x)  (((x) >> 16) & IOCPARM_MASK)
#define IOCBASECMD(x)   ((x) & ~(IOCPARM_MASK << 16))
#define IOCGROUP(x)     (((x) >> 8) & 0xff)
 
#define IOCPARM_MAX     (1 << IOCPARM_SHIFT) /* max size of ioctl */
#define IOC_VOID        0x20000000  /* no parameters */
#define IOC_OUT         0x40000000  /* copy out parameters */
#define IOC_IN          0x80000000  /* copy in parameters */
#define IOC_INOUT       (IOC_IN|IOC_OUT)
#define IOC_DIRMASK     (IOC_VOID|IOC_OUT|IOC_IN)
 
#define _IOC(inout,group,num,len)   ((int) \
    ((inout) | (((len) & IOCPARM_MASK) << 16) | ((group) << 8) | (num)))
#define _IO(g,n)        _IOC(IOC_VOID,  (g), (n), 0)
#define _IOWINT(g,n)    _IOC(IOC_VOID,  (g), (n), sizeof(int))
#define _IOR(g,n,t)     _IOC(IOC_OUT,   (g), (n), sizeof(t))
#define _IOW(g,n,t)     _IOC(IOC_IN,    (g), (n), sizeof(t))
/* this should be _IORW, but stdio got there first */
#define _IOWR(g,n,t)    _IOC(IOC_INOUT, (g), (n), sizeof(t))
 
#ifdef __cplusplus
extern "C" {
#endif
 
int ioctl(int fd,
          int request,
          ...);
 
#ifdef __cplusplus
}
#endif